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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="http://code.jquery.com/jquery-2.1.1.min.js"></script>

</head>

<body>
    <script>
        let myPromise = url => $.ajax({ url: url })

        myPromise('../data/1.json')
            .then(res => {
                console.log(res)
                return res.count >= 0 ? myPromise('../data/2.json') : '';
            })
            .then(res => {
                console.log(res)
                return res.count >= 1 ? myPromise('../data/3.json') : '';
            })
            .then(res => console.log(res))

        console.log('----------------------同步')

        let myPromise1 = url => $.ajax({ url: url })

        myPromise1('../data/1.json')
            .then(res => {
                console.log(res);
                return res.count >= 0 ? myPromise1('../data/2.json') : ''
            })
            .then(res => {
                console.log(res);
                return res.count >= 1 ? myPromise1('../data/3.json') : ''
            })
            .then(res => console.log(res))

        console.log('----------------------同步')

        let myPromise2 = url => $.ajax({ url: url })
        myPromise2('../data/1.json')
            .then(res => {
                console.log(res);
                return res.count >= 0 ? myPromise2('../data/2.json') : ''
            })
            .then(res => {
                console.log(res);
                return res.count >= 1 ? myPromise2('../data/3.json') : ''
            })
            .then(res => console.log(res))

    </script>
</body>

</html>